New technical advances in swivel walkers

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1 Prosthetics and Orthotics International, 2003, 27, New technical advances in swivel walkers J. STALLARD*, B. LOMAS**, P. WOOLLAM*, I. R. FARMER*, N. JONES*, R. POINER* and K. MILLER* *Orthotic Research & Locomotor Assessment Unit (ORLA U), Robert Jones and Agnes Hunt Orthopaedic and District Hospital NHS Trust, Oswestry, Shropshire, UK **Consort Engineering Ltd, Commercial Brow, Hyde, Cheshire UK Abstract Swivel walkers were commonly prescribed for children with complete thoracic lesion myelomeningocele in the 1970s and 80s, when the incidence of spina bifida in the UK was of the order of 3 per 100,000 live births. The advent of reciprocal walking orthoses provided a more suitable alternative for those with good upper limb and trunk function, and swivel walkers were then used primarily for very young or more severely disabled patients. Pre-natal screening has dramatically reduced the incidence of spina bifida in the UK and subsequently swivel walkers have been used in a wider range of pathology, including spinal muscular atrophy, multiple sclerosis, muscular dystrophy and other neurological conditions that lead to lower limb dysfunction. The detail design of these devices has been adapted to accommodate the specific problems encountered in these conditions. In particular the designs have been updated to: enable very young patients to be more readily fitted at the age of 1 year; allow the walking mechanisms to be conveniently adjusted for easier ambulation when weakness or lack of confidence inhibits performance; permit simple adjustment to a standing frame mode to enhance stability in situations of increased risk; promote manual handling practice that is compatible with the National Health All correspondence to be addressed to John Stallard, ORLAU, Robert Jones and Agnes Hunt Orthopaedic and District Hospital NHS Trust, Oswestry, Shropshire SY10 7AG, UK. 132 Service (NHS) policy of compliance with relevant regulations. To underpin appropriate prescription and safe supply the NHS Procurement Agency have encouraged the development of a common course for all types of swivel walker. Introduction Swivel walkers were first developed for disabled children in the 1960s (Spielrein, 1964; Motloch and Elliott, 1966). At about that time children with spina bifida had presented to orthopaedic surgeons in increasing numbers because of the beneficial effects of the Spitz- Holter valve in relieving hydrocephalus (Drake and Sainte-Rose, 1995). The incidence of the condition grew to alarming proportions in some areas of the UK, with rates in North Wales, for instance, being as high as 4.2 per thousand live births (Rose, 1971). Initial treatment strategies had been disappointing in achieving the objective of improved mobility. Lorber (1971), for example, showed that in a cohort of 41 patients with spina bifida who had been subjected to 333 orthopaedic procedures, none of them were ambulators. It was this general situation that prompted a move to multi-disciplinary integration of treatment strategies and the introduction of more effective orthotic devices for walking (Rose, 1980). Swivel walkers (Motloch and Elliott, 1966); Edbrooke, 1970) consist of an exoskeletal frame to provide internal stabilisation and prevent the patient from collapsing under themselves, and swivelling footplates which provide stable standing and permit forward progression as the patient rocks from side to side (Fig. 1). They

2 became a commonly prescribed orthosis for patients with thoracic lesion spina bifida because of the ease with which ambulation could be made a realistic ambition. Refinements in design occurred as experience identified the need for detailed improvements (Rose and Henshaw, 1972; Griffiths et al, 1980; Farmer et al, 1982; Butler et al, 1982). As a result patients became even more adept in their ability to ambulate (Rose et al, 1983). The expectation that therapeutic benefit would be achieved through walking had initially been on the basis of reasonable supposition, supported by anecdotal clinical evidence. Carroll (1974), Rose (1976) and Menelaus (1987) all identified the benefits of improved urinary drainage, bowel function and reduction in bone fractures to be anticipated in ambulatory patients. Subsequent research on a group of 36 matched pairs of patients with spina bifida (Mazur et al., 1989) provided strong evidence of the reduction in pressure sores and bone fractures that early introduction of regular walking activity could achieve. Over an approximate ten year period they showed that non-walkers had five times the number of pressure sores and twice the number of bone fractures. They also identified greater levels of independence in a wide range of activities of daily living, and nearly four times the level of L Fig. 1. A typical swivel walker. New technical advances in swivel walkers 133 independent mobility within the community for patients who used orthoses for regular ambulation. Amongst the other advances that occurred in response to the challenges presented by the aspiration to achieve effective ambulation for children with spina bifida was a range of reciprocal walking orthoses (Rose, 1979; Douglas et al, Butler and Major 1987; Jaspers et al, 1997). It became widely accepted that this form of walking was the most effective for children from the age of five, provided that the patient had good upper limb function and coordination (Phillips etal, 1995). However, there remained a substantial number of patients for whom this form of walking was not a realistic expectation. Although there was a diminution in the numbers of swivel walkers prescribed, they remained an important option for very young patients, and those with upper limb involvement or other conditions contra-indicating the use of reciprocal walking orthoses. Experience in using swivel walkers for patients with myelomeningocele led to a recognition of their potential in other disabling conditions. Spinal muscular atrophy, multiple sclerosis, and particularly muscular dystrophy are all pathologies for which swivel walkers have provided a useful form of therapeutic and functional walking. This has meant that swivel walkers have retained a place in the armoury of treatment options for most forms of paraplegia, despite the pleasingly large reduction in the incidence of spina bifida and other congenital conditions that pre-natal screening (Alfirevic et al, 2002) has achieved in the UK and a number of other countries. The only major contraindicating condition for swivel walkers is severe athetosis, because of the potential for such patients to set up dynamic effects that overcome the inherent stability of the device. As the potential for prescription has broadened the requirements have similarly expanded. This has demanded subtle changes in design related to the variations of pathological condition which have been encountered. For example, the special difficulties of muscular dystrophy patients have led to refinements (Stallard et al, 1992) that make it possible to more effectively maintain ambulation beyond the point when they would otherwise be confined solely to a wheelchair. Other, more recent, refinements have occurred that have

3 134 J. Stallard, B. Lomas, P. Woollam, I. R. Farmer, N. Jones, R. Poiner and K. Miller Fig. 2. Mechanics of propulsion. extended the potential for provision of therapeutic ambulation for patients in which other forms of walking are impractical. The changing circumstances in which patients now enjoy their educational experience have also required innovative responses to enable swift changes of orthotic function to match the specific demands of the different elements of academic and physiotherapy practice. Swivel walker mechanics For any form of walking to be effectively undertaken it is necessary to ensure that the joints of the lower limbs are stabilised. In paraplegic patients this is achieved by providing three point fixation of the hips and knees with appropriate control of the ankles. Swivel walkers have mechanisms that provide both stabilisation and a means of propulsion (Stallard et al., 1986). As shown in Figure 1, they incorporate thoracic band, sacral band, knee bar and foot location arrangements that prevent the anatomical joints of the patient from flexing under the influence of gravity. Footplates on the bottom of the orthosis provide sufficient support area within which the centre of gravity of the patient can be located so as to prevent the intrinsically stable patient toppling over. Propulsion (Fig. 2) is achieved by the patient rocking from side to side on the footplates (that are slightly angled upwards (dihedral angle) from the inner edge). Sideways inertial forces during rocking create a forward turning moment about the grounded footplate bearing - the degree of forward swivel being controlled by a stop mechanism. A rhythmic rocking provides the most efficient manifestation of the propulsion mechanism. Fig. 3. Swivel walker for infants. Walking backwards is possible by thrusting more to the rear during rocking so as to ensure the inertial reaction is behind the footplate bearing, but this is more difficult to achieve. Recent advances Infant orthosis The potential to use swivel walkers for very young patients has always been recognised. However, adapting existing designs to their diminutive dimensions had never been entirely satisfactory. This issue has now been addressed with a design specifically developed for patients in the one to three year old age range (Fig. 3). It has conventional fastenings that can be readily adjusted to the rapidly changing shape of patients in this category, but which are as convenient as possible for adults to secure and release, whilst being beyond the capacity of the patient to operate. The need for lightweight but stiff structures that are sufficiently robust for the general environment within which they are used has been satisfied by adopting aluminium alloy components that have good section moduli. (b) Clinical Experience Since its development 11 patients ranging from 12 months to two years of age have been supplied with the new design. Other models of

4 New technical advances in swivel walkers 135 swivel walker had been rejected because they did not satisfactorily accommodate the small dimensions of this group. The patients were able to commence independent ambulation between the ages of 18 months and two years, after appropriate physiotherapy training. Outriggers!standing frame The changing circumstances in which disabled children receive education in a more integrated environment is almost universally welcomed. However, for those responsible for providing therapeutic care this presents new challenges, particularly when ambulation in a normal school is a primary objective. Teachers frequently find a swivel walker in the classroom a responsibility that is difficult to manage because of perceived instability with other children who are used to moving about unhindered by the need to take care of the special requirements of one individual. This can present an inconvenience so great as to inhibit therapeutic walking. Standing frames have been seen as a more acceptable compromise within the classroom, but do not permit the additional advantages of ambulation. To overcome this problem a converter frame that enables, a swivel walker to be changed into a standing frame in seconds, and vice versa, has been developed (Fig. 4). Patients can now be safely located in the classroom (or other environment) in standing frame mode, then have the system rapidly changed into a swivel walker when ambulation can be more safely adopted. The converter frame was seen to provide Fig. 4. Swivel walker to standing frame converter advantages over standard standing frames. Consequently a pure standing frame version has now been developed that provides the greater degree of clearance around fixed objects that the converter frame was observed to provide. (b) Clinical experience Since the development of the system two patients with existing swivel walkers have had outriggers fitted at the request of the physiotherapist in the school which they attend. The reaction of teachers was very positive because of the perceived level of increased stability and safety within the classroom. Conversion time was less than one minute and this enabled the physiotherapist to permit the child to ambulate at will during lunchtime breaks and scheduled therapy time. This was found to sustain the patient's interest in upright mobility, which served the therapeutic objectives of the clinicians. This experience has led to a further six swivel walkers being supplied with outrigger converters from new - all with the same overall objective of sustaining therapeutic benefit. Satisfactory trials of the standing frame version of the system have been concluded with two children and one adult patient, and this is now offered as a routine option. Hoisting eyes Historically the transfer from sitting to standing and vice versa of ambulatory patients with severe disability relied on the manual intervention of a single carer. This was a strategy that carried a high risk of back injury for those who cared for individuals using orthoses to walk. The introduction and widespread adoption of the Manual Handling Operations Regulations (Health and Safety Executive, 1992) has led to a profound change in attitude to the task of transferring patients and significantly reduced the potential for injury to carers. Paradoxically it puts at risk the hard won advantages of walking for many severely disabled people and a resolution of the difficulty of transfer is essential to ensure that this group of patients can continue to experience the therapeutic and functional benefits of ambulation. As a consequence of the new policy manual handling aids have become much more readily available in clinical departments. In order to

5 136 /. Stallard, B. Lomas, P. Woollam, I. R. Farmer, N. Jones, R. Poiner and K. Miller the previously adopted practice, the need for adjustment has become more important. Consequently swivel walkers now have footplate step length adjustment incorporated as standard. This is achieved via a screw adjustment that is accessible between the baseplate of the exoskeletal structure and the upper part of the footplates. Fig. 5. Hoisting eye for ease of transfer. address the transfer problem for swivel walkers a strategy has been devised for transfer using electric or hydraulic hoists. This is now included in the documentation accompanying each swivel walker, and for most models (Fig. 5) hoisting eyes are available to more conveniently enable this strategy. (b) Clinical experience Since the completion of the development the use of hoisting eyes on swivel walkers has become a routine procedure in ORLAU in combination with a Liko electric hoist. Whereas direct lifting of a swivel walker from the floor was judged to be contrary to good practice, the Manual Handling Supervisor approves of this method. Footplate step length adjustment When swivel walkers were first designed for patients with myelomeningocele they were set up for optimal performance from those with good upper limb and trunk function, because there were no effective alternatives. The advent of reciprocal walking diminished the numbers in this category that wished to use a swivel walker beyond the age of 5 years. Experience has shown that for patients with additional upper limb and trunk control problems (i.e. currently the most common group) ease of walking has become the main priority, rather than speed of progression. It has become clear that optimising ease of walking requires careful adjustment of the step length stop on the footplates. Whereas simplicity of manufacture with a common step length was (b) Clinical experience Patients with thoracic lesions that have poor strength in the trunk and arms can use swivel walkers effectively, provided the mechanics are adjusted sensitively. Step length setting becomes critical for this group in order to optimise performance, whilst avoiding a position that prevents them injecting sufficient energy to advance to the next step. Clinical experience has shown that, in particular, enabling patients with muscular dystrophy (MD) to ambulate in a swivel walker demands careful adjustment of the footplate settings. A common finding on earlier models of swivel walker that had a standardised step length was that these patients would frequently become stuck when maximum advancement of step position had been achieved. The provision of variation of step length has enabled adjustment of maximum position so as to avoid this situation for three patients supplied by ORLAU since its introduction. Discussion Swivel walkers have a long history of providing a useful form of ambulation for patients with thoracic spinal lesions. They have been successfully applied with complete lesions as high as C6, and in patients as young as 1 year old up to those qualifying for old-age pension. In the home or school environment functional activities requiring the use of hands in the upright position are possible in safety and comparative comfort. Whilst reciprocal walking orthoses are now frequently the orthosis of choice for patients with good bilateral upper limb function and co-ordination, swivel walkers continue to provide an important option where more severe disability makes those devices impractical. Continuous development in the light of field experience has enabled many of the problems encountered with a variety of pathological conditions to be more effectively resolved. This has led to a recognition that patients must be

6 carefully assessed to ensure that their requirements are fully appreciated. It is also essential that swivel walkers (as with all walking orthoses) are supplied in an environment in which all elements of the treatment system are properly evaluated, delivered and reviewed. In the UK the NHS Purchasing and Supply Agency has been anxious to ensure that this happens and have made specific training in the techniques for supply an element of the model orthotics contract (NHS Executive, 1995). They have put in place measures that ensure training is available for those professionals that wish to supply swivel walkers by promoting a common training package delivered by professionals familiar with all the swivel walkers that are currently available (ORLAU, 2001). Long-term experience with swivel walkers has shown that they are mechanically reliable. Whilst they are comparatively inexpensive relative to other lower limb devices, they necessarily represent a significant financial investment. In order to provide opportunities for prudent economy arrangements have been agreed with the UK Medical Devices Agency (MDA) for requested refurbishment of used swivel walkers by manufacturers specifically approved to do so by the MDA, for supply to new patients. This is a carefully controlled arrangement that satisfies the essential requirements of the Medical Devices Directive (European Council, 1993) by ensuring that the components are fit for purpose and remain traceable, and that manufacturer's guarantees are still in force. New technical advances in swivel walkers 137 REFERENCES ALFIREVIC Z, GOSDEN CM, NEILSON JP (2002). Chorion villus sampling versus amniocentesis for prenatal diagnosis (Cochrane Review). In: The Cochrane Library, 1, Oxford: Update Software. BUTLER PB, FARMER IR, POINER R, PATRICK JH (1982). Use of the ORLAU Swivel Walker for the severely handicapped patient. Physiotherapy 68, BUTLER PB, MAJOR RE (1987). The ParaWalker:/a rational approach to the provision of reciprocal ambulation for paraplegic patients. Physiotherapy 73, CARROLL N (1974). The orthotic management of the spina bifida child. Clin Orthop 102, DOUGLAS R, LARSON P, D'AMBROSIA R, MCCALL RE (1983). The LSU reciprocation gait orthosis. Orthopedics 6, DRAKE JM, SAINTE-ROSE C (1995). The Spitz-Holter valve: the shunt book.-cambridge, Mass: Blackwell Science Inc. EDBROOKE H (1970). The Royal Salop Infirmary, 'Clicking splint'. Physiotherapy 56, EUROPEAN COUNCIL (1993). Council Directive 93/42/EEC concerning medical devices. ISSN L 169 Vol 36. FARMER IR, POINER R, ROSE GK, PATRICK JH (1982). The adult ORLAU swivel walker - ambulation for paraplegic and tetraplegic patients. Paraplegia 20, GRIFFITHS JC, HENSHAW JT, HEYWOOD OB, Taylor A.G. (1980). Clinical applications of the paraplegic swivel walker. J Biomed Eng 2, HEALTH & SAFETY EXECUTIVE (1992). Manual Handling Operations Regulations. Conclusion Swivel walkers are continuing to provide therapeutic and functional walking for patients with high thoracic spinal lesions and additional upper limb difficulties. Recent detail advances have enhanced their ability to do this and make provision of this form of ambulation practical for an even wider range of pathologies and impairments. The widespread acceptance of therapeutic benefit in walking for severely disabled patients (Carroll, 1974; Rose, 1976; Menelaus, 1987) and the confirmation of this by Mazur et al., (1989), strongly suggest that ambulation for this group is a worthwhile clinical objective. The reported advances ensure that swivel walkers remain one of the simplest and most effective means of achieving this. JASPERS P, PEERAER L, VAN PETERGEM W, VAN DER PERRE G (1997). The use of an advanced reciprocal gait orthosis by paraplegic individuals: a follow-up study. Spinal Cord 35, LORBER J (1971). Results of treatment of myelomeningocele. Dev Med Child Neurol 13, MAZUR JM, SHURTLEFF D, MENELAUS M, COLLIVER J (1989). Orthopaedic management of high-level spina bifida. J Bone Joint Surg 71A, MENELAUS MBD (1987). Progress in the management of the paralytic hip in myelomemingocele. Orthop Clin North Am 11, MOTLOCH WM AND ELLIOTT J (1966). Fitting and training children with swivel walkers. Artificial Limbs, 10(2), NHS EXECUTIVE (1995). Health Service Guidelines: Contracting for orthotic services. HSG(95)47 on

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